Raritan River Clays

The economic success of the Sayre and Fisher Company and its successor, the Sayre and Fisher Brick Company, depended to a large extent on the availability of a plentiful supply of clay. The clay deposits mined by Sayre and Fisher were part of the Woodbridge Clays of the Raritan Formation of the Cretaceous age (see 1904 geological map; Early Clay Mining; Later Clay Mining). Woodbridge Clays range in thickness from 50 to 80 feet and were well suited for brick and pottery manufacture. The erosional processes along the shores of the Raritan River have removed massive volumes of clay, but also exposed clay beds for convenient access and provided affordable means of transportation of clay and clay products.

The upper layers of Woodbridge Clays consist of black clay with some lignite and pyrite, alternating with thin seams of white quartz sand. These black clays were used extensively around Sayreville for hollow brick, fireproofing, and common brick (see clay pits). Common brick was used for the portions of structures where appearance was of lesser concern. The lower layers of Woodbridge Clays include high-grade clays of light blue, grey and mottled clays.

Higher quality clays were used in manufacturing pressed and front brick, which were used for decorative purposes. The clays used to manufacture enamel brick were a mix of different fire clays and clay loams. Enamel bricks had a coating of enamel on one or two sides (Ries and Kummel,1904: 182-223).